How to do sliding like Crysis and/or FarCry?

Using the crouch and run script by Aldo (awesome script), I have added sliding. Set slideSpeed and slideTimerMax. When sliding, the player can look around, but not change direction.

 #pragma strict
 
 var walkSpeed: float = 7; // regular speed
 var crchSpeed: float = 3; // crouching speed
 var runSpeed: float = 20; // run speed
 
 private var chMotor: CharacterMotor;
 private var ch: CharacterController;
 private var tr: Transform;
 private var height: float; // initial height
 
 public var slideSpeed: float = 20; // slide speed
 private var isSliding : boolean = false;
 private var slideForward : Vector3; // direction of slide
 private var slideTimer : float = 0.0;
 public var slideTimerMax : float = 2.5; // time while sliding
 
 function Start()
 {
     chMotor = GetComponent(CharacterMotor);
     tr = transform;
     ch = GetComponent(CharacterController);
     height = ch.height;
 }
 
 function Update()
 {
     var h = height;
     var speed = walkSpeed;
     
     // - run and crouch -    
     if (ch.isGrounded && Input.GetKey("left shift") || Input.GetKey("right shift")) // press Shift to run
     {
         speed = runSpeed;
     }
     if (Input.GetKey("c")) // press C to crouch
     {
         h = 0.5 * height;
         speed = crchSpeed; // slow down when crouching
     }    
     
     // - slide -    
     if (Input.GetKeyDown("f") && !isSliding) // press F to slide
     {
         slideTimer = 0.0; // start timer
         isSliding = true;
         slideForward = tr.forward;
     }
     if (isSliding)
     {
         h = 0.5 * height; // height is crouch height
         speed = slideSpeed; // speed is slide speed
         chMotor.movement.velocity = slideForward * speed;
         
         slideTimer += Time.deltaTime;
         if (slideTimer > slideTimerMax)
         {
             isSliding = false;
         }
     }    
     
     // - apply movement modifiers -    
     chMotor.movement.maxForwardSpeed = speed; // set max speed
     var lastHeight = ch.height; // crouch/stand up smoothly 
     ch.height = Mathf.Lerp(ch.height, h, 5 * Time.deltaTime);
     tr.position.y += (ch.height - lastHeight) / 2; // fix vertical position
 }